The emergence of subunit vaccines created by recombinant DNA technology has intensified the need for safe and effective adjuvant-containing compositions. Subunit vaccines, while offering significant advantages over traditional live and killed vaccines in terms of safety and cost of production, generally present isolated polypeptides or mixtures of isolated polypeptides to the immune system, which have limited immunogenicity as compared to, for example, whole viruses, bacteria and other microorganisms. As a result, these vaccines generally benefit from adjuvants with immunostimulatory capabilities, which help them to reach their full potential in treating disease.
Traditional live vaccines, on the other hand, commonly do not require adjuvants. Moreover, killed vaccines are generally more immunogenic than subunit vaccines and commonly do not require adjuvants. Nonetheless, these vaccines, like subunit vaccines, can also benefit from adjuvants with immunostimulatory capabilities.